Principle of Adsorption Regeneration of Transformer Oil

What is the principle of adsorption regeneration of transformer oil? What two methods are there usually? What are the factors that affect adsorption regeneration?

Adsorption regeneration is to use the adsorbent with a large active surface area and a strong adsorption capacity for oxidation products and water in the waste transformer oil, so that the adsorbent can fully contact the waste transformer oil, thereby removing harmful substances in the oil, to achieve the purpose of Transformer Oil Purification and regeneration.

The adsorption process is divided into two steps. First, the adsorbed substances diffuse from the oil to the outer surface of the adsorbent, and then further adsorb on the inner surface of the adsorbent. The adsorption is selective, and the polar substances in the oil, such as organic compounds containing ammonia, sulfur and oxygen, are adsorbed first, followed by polycyclic aromatic hydrocarbons. At low temperature, the adsorption of naphthenic acid is not very efficient.

There are usually two methods of contact regeneration and filter regeneration.

The contact method is a regeneration method in which a powdered adsorbent (such as activated clay, 801 adsorbent, etc.) is directly contacted with oil. When the oil deterioration is not serious, the oil color is not dark, the acid value is below 0.1mgKOH/g oil, the water-soluble acid appears in the oil or the tanδ rises significantly, the effect of this method is better.

The filtration method is a regeneration method in which the adsorbent is installed in the filter and the oil is circulated through the filter to achieve the refining effect. This method is applicable to on-site treatment and live treatment. This is very effective for mildly degraded oils.

standalone Transformer Oil Regeneration Device

The main factors affecting adsorption regeneration are as follows:

(1) The type and shape of the adsorbent. It goes without saying that different adsorbents have different active surfaces and, of course, different adsorption capacities. The larger the active surface, the stronger the adsorption capacity. Generally, activated alumina (800~1500m²/g) is larger than 801 adsorbent (530m²/g), larger than silica gel (300~450m²/g) and larger than activated clay (100~150m²/g). Generally speaking, it has little effect on the shape of the adsorbent, but it still has a little effect. The powder shape is better than the spherical shape and the amorphous shape, which is mainly because the inner surface of the powder shape can be used more fully. However, the resistance of the powder is large, and it is not suitable for the filtration method.

(2) Temperature. Each adsorbent has an optimum adsorption temperature, such as activated clay is 100~150℃, silica gel is 30~50℃, activated alumina is 50~70℃, and 801 adsorbent is 50~60℃. Because adsorption is a reversible process, there may be adsorption and desorption. If the temperature is too high, the desorption capacity may increase, which is unfavorable. If the temperature is too low, on the one hand, the viscosity is high and the diffusion becomes slow, which is not good for adsorption. , the decrease of adsorbent activity is not conducive to adsorption, so it should be controlled at their respective optimal temperatures.

(3) Contact time, from the principle, the adsorption process is divided into two steps, which requires a certain time, too short can not achieve the purpose of adsorption, too long is a waste. Therefore, for the contact method, generally 30~60min is enough. For the filtration method, the flow rate of the oil in the filter is controlled. Generally, the control flow rate should not exceed 2000L/h, so that the oil and the adsorbent have enough time.

(4) It is related to the water content, because the activity of the adsorbent is related to the water content. Too high or too low water content will affect its activity. Therefore, when drying the adsorbent, the temperature must be controlled at the optimum temperature, which is more conducive to adsorption.

PureTech designs and manufactures both online Transformer Oil Regeneration plant and standalone oil regeneration plant. Online transformer oil regeneration plant works together with vacuum Transformer Oil Dehydration, to achieve the purpose of impurity-removal, water-removal, gas-removal, as well as oil regeneration with one machine; and standalone oil regeneration plant only for transformer oil regeneration (acid-removal, oxides-removal) and impurity removal. So user can select the most suitable type based on your needs.

More information please don't hesitate to contact PureTech Oil Filtration Team.